Quoted from the False or Misleading Representations and Deceptive Marketing Practices page, of the Canadian Competition Bureau's website.

"Advertising Dos and Don'ts

The following "Dos and Don'ts" will help businesses comply with the Competition Act.
Dos

-Do avoid fine print disclaimers. They often fail to change the general impression conveyed by an advertisement. If you do use them, make sure the overall impression created by the ad and the disclaimer is not misleading.
-Do fully and clearly disclose all material information in the advertisement.
-Do avoid using terms or phrases in an advertisement that are not meaningful and clear to the ordinary person.
-Do charge the lowest of two or more prices appearing on a product.
-Do ensure that you have reasonable quantities of a product advertised at a bargain price.
-Do, when conducting a contest, disclose all material details required by the Act before potential participants are committed to it.
-Do ensure that your sales force is familiar with these "Dos and Don'ts." Advertisers may be held responsible for representations made by employees.

Don'ts

-Don't confuse "regular price" or "ordinary price" with "manufacturer's suggested list price" or a like term. They are often not the same.
-Don't use "regular price" in an advertisement unless the product has been offered in good faith for sale at that price for a substantial period of time, or a substantial volume of the product has been sold at that price within a reasonable period of time.
-Don't use the words "sale" or "special" in relation to the price of a product unless a significant price reduction has occurred.
-Don't run a "sale" for a long period or repeat it every week.
-Don't increase the price of a product or service to cover the cost of a free product or service.
-Don't use illustrations that are different from the product being sold.
-Don't make a performance claim unless you can prove it, even if you think it is accurate. Testimonials usually do not amount to adequate proof.
-Don't sell a product above your advertised price.
-Don't unduly delay the distribution of prizes when conducting a contest.
-Don't make any materially misleading product warranty or guarantee, or promise to replace, maintain or repair an article.
-Don't use the results of product performance tests and/or testimonials in your advertising unless you are authorized to use them; or if you are authorized to use them, don't distort test results or the scope of testimonials.
-Don't forget that no one actually needs to be deceived or misled for a court to find that an advertisement is misleading".